Bulletin of the American Physical Society
2011 Fall Meeting of the APS Division of Nuclear Physics
Volume 56, Number 12
Wednesday–Saturday, October 26–29, 2011; East Lansing, Michigan
Session FD: Instrumentation III |
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Chair: Yordanka Ilieva, South Carolina Room: Heritage |
Thursday, October 27, 2011 4:00PM - 4:12PM |
FD.00001: Facilitating Precision Mass Measurements at CARIBU Daniel Lascar, Jon Van Schelt, Guy Savard, Ralph Segel, Jason Clark, Kumar Sharma, Shane Caldwell, Li Gang, Matthew Sternberg, John Greene, Anthony Levand, Bruce Zabransky The Canadian Penning Trap Mass Spectrometer (CPT) has begun a campaign of precision mass measurements of neutron-rich nuclei produced via spontaneous fission of $^{252}$Cf as part of the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) to the ATLAS facility at Argonne National Laboratory. As of the time of submission of this abstract, we have measured neutron rich isotopes of Cs, I, Te, Sb, and Sn. CARIBU is currently running with a 60 mCi source of $^{252}$Cf which will be upgraded to a 1 Ci source in the future. In order to make this campaign possible, several upgrades to the CARIBU and CPT system were required including a new Radio Frequency Quadrupole (RFQ) ion buncher to CARIBU's low energy beamline, cryogenic cooling of the RFQ Paul trap below the CPT, and an electrostatic elevator to allow for transport of ion bunches from a 50 kV platform to the CPT system's 2 kV beamline. Construction and commissioning of the buncher and modified Paul Trap will be discussed as well as their impact on the measurements in this campaign. [Preview Abstract] |
Thursday, October 27, 2011 4:12PM - 4:24PM |
FD.00002: Commissioning a Tape Transport System for Decay Studies and Beam Diagnostics at CARIBU P.F. Bertone, B. Digiovine, C.J. Lister, K. Teh, F.G. Kondev, C. Nair, P. Chowdhury, A.Y. Deo, S. Lakshmi The CAlifornium Rare Isotope Breeder Upgrade (CARIBU) to the ATLAS facility at Argonne utilizes the spontaneous fission of $^{252}\textnormal{Cf}$ for producing neutron-rich radioactive nuclei. CARIBU will be used for a wide variety of experiments, involving both reaccelerated and stopped beams, in nuclear structure, nuclear astrophysics and applications. Many of these experiments will require a means of transporting radioactivity to and from detector counting stations for the purpose of assaying beam content, measuring half-lives, $\beta$-$\gamma$ spectroscopy and determining Gamow-Teller strength distributions. We have commissioned the first of several tape transport systems that will perform these functions. An overview of the design and deployment of the system will be given along with preliminary test results. [Preview Abstract] |
Thursday, October 27, 2011 4:24PM - 4:36PM |
FD.00003: New detector array - the HRIBF Modular Total Absorption Spectrometer Marzena Wolinska-Cichocka, Krzysztof Rykaczewski, Marek Karny, Aleksandra Kuzniak, Robert Grzywacz, Charlie Rasco, David Miller, Carl J. Gross, Jim Johnson The construction of a new Modular Total Absorption Spectrometer (MTAS) at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory will be presented. The total absorption gamma spectra measured with MTAS will be used to derive a true beta-feeding pattern and resulting beta strength function for fission products. In particular, the measurements of decay heat released by radioactive nuclei produced in nuclear fuels at power reactors will be performed. MTAS is made up of 19 large NaI(Tl) crystals each encapsulated with a 0.8-mm-thick carbon fiber. There are also two 1-mm- thick Silicon Strip Detectors surrounding a moving tape collector that count beta-energy loss signals. The structure is shielded by more than 1-inch of lead around MTAS which reduces background radiation significantly. MTAS efficiency for full energy deposition of gamma ray approaches nearly 90\% for 300 keV gammas and over 75\% for a 5 MeV gamma transition. [Preview Abstract] |
Thursday, October 27, 2011 4:36PM - 4:48PM |
FD.00004: Vertical Charge Exchange Cell for Collinear Laser Spectroscopy at NSCL Andrew Klose, Kei Minamisono, Nadja Froemmgen, Christopher Geppert, Michael Hammen, Joerg Kraemer, Andreas Krieger, Phil Levy, Paul Mantica, Wilfried Noertershaeuser, Sophia Vinnikova A vertical charge exchange cell (CEC), originally developed at TRIUMF/ISAC, has been constructed at NSCL for the Beam Cooling and Laser Spectroscopy (BECOLA) system. The CEC was initially commissioned at the TRIGA-Laser facility at the University of Mainz by neutralizing a 10 keV Rb$^{+}$ ion beam with K vapor. The neutralization efficiency was measured as a function of the CEC heater temperature. The line shape of the Rb D2 transition was also examined in relation to the neutral fraction of the Rb beam. Details of the CEC design and operation, as well as the results of the tests will be discussed. [Preview Abstract] |
Thursday, October 27, 2011 4:48PM - 5:00PM |
FD.00005: Status of the ReAccelerator Facility ReA for Rare Isotopes Daniela Leitner, John Popielarski, Alain Lapierre, Fernando Montes, Georgios Perdikakis, Stefan Schwarz, Walter Wittmer, Xiaoyu Wu The Facility for Rare Isotope Beams (FRIB) at Michigan State University (MSU) is currently in the preliminary design phase. FRIB consists of a heavy ion driver LINAC, followed by a fragmentation target station, a fragment separator, a gas stopping area, experimental areas for fast and stopped beams, and a ReAccelerator facility (ReA). In its final configuration, ReA will provide heavy ion beams from 0.3 MeV/u to 12 MeV/u for heaviest ions and up to 20 MeV/u for light ions. The first stage of ReA is already under commissioning and will be connected to the Coupled Cyclotron Facility at MSU by the end of 2012. The front end of the accelerator consists of a gas stopper, an Electron Beam Ion Source/Trap (EBIT) charge state booster, a room temperature RFQ, followed by a short SRF LINAC. An overview and status of the ReA facility will be presented and will be focused on the testing and ongoing beam commissioning. A schedule for the completion of the first stage and proposed energy upgrades will be described. In addition, the beam line layout of the experimental hall will be described. [Preview Abstract] |
Thursday, October 27, 2011 5:00PM - 5:12PM |
FD.00006: Summing NaI(Tl) detector (SuN) for radioactive beam experiments relevant for the p-process Anna Simon, Ilya Beskin, Sean Liddick, Karthik Padmanabhan, Jessica Peace, Stephen Quinn, Artemis Spyrou, Benjamin Stefanek P-process refers to ($\gamma $,p), ($\gamma $,$\alpha )$ and ($\gamma $,n) reactions producing nuclei on the neutron-deficient side of the valley of stability that cannot be reached by s- and r-processes. This process can be investigated via inversed reactions, i.e. proton or alpha capture with gamma emission. Gamma spectra resulting from capture reactions, may be complicated in structure and as such difficult to analyze. However, this difficulty may be omitted by implementing a summing technique, for which all gamma rays emitted during the decay cascade are summed into one peak, so called ``sum peak.'' Thus, in ideal case, the resulting spectrum will comprise of one peak of the energy E=E$_{cm}$+Q. This technique has already been successfully tested during stable beam experiments. In order to apply this technique to radioactive beam experiments a new Summing NaI(Tl) (SuN) detector was designed at NSCL. It is a 16x16 inch cylindrical barrel divided into eight optically separated segments, each of them read by three photomultipliers. Each of the PMTs is read independently by a digital data acquisition system (DDAS) and the final sum spectrum is obtained by software summing of the individual spectra. Here, first results obtained with the SuN detector as well as its possible future applications will be presented. [Preview Abstract] |
Thursday, October 27, 2011 5:12PM - 5:24PM |
FD.00007: Designing Magnetic Coils From the Inside Out Daniel Wagner Traditionally the design cycle for magnetic fields involves guessing at a reasonable conductor and magnetic material configuration, using finite element analysis (FEA) software to calculate the resulting field, modifying the configuration, and iterating to produce the desired results. We take the opposite approach of specifying the required magnetic field, imposing it as a boundary condition on the region of interest, and then solving the Laplace equation to determine the field outside that region. The exact conductor configuration along the boundaries is extracted from the magnetic scalar potential in a trivial manner. This method is being applied to design a coils for the neutron EDM experiment, and an RF waveguide in a new design of a neutron resonant spin flipper for the n-3He experiment. Both experiments will run at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. [Preview Abstract] |
Thursday, October 27, 2011 5:24PM - 5:36PM |
FD.00008: Simulation of the NSCL Cyclotron Gas Stopper Ninad Joshi, Georg Bollen, Shailendra Chouhan, David Morrissey, Stefan Schwarz Thermalization in a buffer gas is becoming the method of choice for converting beams of rare isotopes produced via projectile fragmentation after in-flight separation into low-energy beams. These beams allow ISOL-type experiments to be conducted on projectile fragmentation products, such as precision mass measurements with traps or laser spectroscopy, and further transport for reacceleration. Currently available systems for high-energy beams employ a linear gas cell design filled with 0.1-1 bar of helium. A new device is being constructed at the NSCL/MSU. The new system is based on slowing down the fast ions in a sector-focusing cyclotron magnet in a chamber filled with Helium buffer gas at low pressure. RF-guiding techniques are used to extract the ions. Compared to linear gas stopper systems such a device promises higher efficiencies and faster extraction in particular for light ion beams and higher beam rate capability. This contribution will summarize the status of the ongoing design of the cyclotron gas stopper, with emphasis on detailed simulations with an optimized magnet including simulations of beam injection and stopping in the full 3D magnetic field. [Preview Abstract] |
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